* {
  /* 初始化 */
  margin: 0;
  padding: 0;
}
body {
  height: 100vh;
  /* 弹性布局 水平+垂直居中 */
  display: flex;
  justify-content: center;
  align-items: center;
  /* 渐变背景 */
  background: linear-gradient(to top left, #84a0f4, #c2e9fb);
}
body::before {
  content: '点击右下角';
  color: #fff;
  font-size: 32px;
  text-shadow: 0 3px 3px #4c6ed3;
}
.menu-box {
  /* 固定定位 右下角 */
  position: fixed;
  bottom: 40px;
  right: 40px;
}
/* 菜单按钮 */
.menu-button {
  width: 50px;
  height: 50px;
  background-color: #5c67ff;
  border-radius: 50%;
  /* 投影 */
  box-shadow: 0 0 0 4px rgba(92, 103, 255, 0.3);
  color: #fff;
  display: flex;
  justify-content: center;
  align-items: center;
  position: relative;
  z-index: 1;
  cursor: pointer;
  /* 过渡 */
  transition: 0.2s ease-in;
}
.menu-button:hover {
  background-color: #4854ff;
  box-shadow: 0 0 0 8px rgba(92, 103, 255, 0.3);
}
.menu-button .line-box {
  width: 20px;
  height: 20px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  cursor: pointer;
  transition: transform 0.3s ease-out;
}
/* 菜单按钮图标（三条杠） */
.menu-button .line {
  background-color: #fff;
  width: 100%;
  height: 2px;
  border-radius: 2px;
}
/* 前后两条短，中间的长 */
.menu-button .line:first-child {
  width: 50%;
  /* 设置变换的基点 */
  transform-origin: right;
  /* 过渡效果 */
  transition: transform 0.3s ease-in-out;
}
.menu-button .line:last-child {
  width: 50%;
  align-self: flex-end;
  transform-origin: left;
  transition: transform 0.3s ease-in-out;
}
/* 菜单列表 */
.menu-list {
  width: 140px;
  height: 160px;
  background-color: #fff;
  border-radius: 8px;
  list-style: none;
  padding: 6px;
  box-shadow: 0 0 4px 4px rgba(92, 103, 255, 0.15);
  position: absolute;
  right: 15px;
  bottom: 15px;
  /* 默认隐藏 */
  opacity: 0;
  transform: scale(0);
  /* 设置变换的基点 */
  transform-origin: bottom right;
  /* 过渡效果 */
  transition: 0.3s ease;
  /* 过渡延迟 */
  transition-delay: 0.1s;
}
/* 菜单项 */
.menu-list li {
  display: flex;
  align-items: center;
  padding: 10px;
  color: #1c3991;
  cursor: pointer;
  position: relative;
  /* 默认隐藏 */
  opacity: 0;
  transform: translateX(-10px);
  transition: 0.2s ease-in;
}
.menu-list li:hover {
  color: #5c67ff;
}
/* 菜单项下边框 */
.menu-list li::before {
  content: '';
  width: calc(100% - 24px);
  height: 1px;
  background-color: rgba(92, 103, 255, 0.1);
  position: absolute;
  bottom: 0;
  left: 12px;
}
/* 最后一项不用下边框 */
.menu-list li:last-child::before {
  display: none;
}
/* 菜单项图标 */
.menu-list .fa {
  font-size: 18px;
  width: 18px;
  height: 18px;
  display: flex;
  justify-content: center;
  align-items: center;
}
/* 菜单项文本 */
.menu-list span {
  font-size: 14px;
  margin-left: 8px;
}
/* 活动态下的部分样式变化 */
/* 三条杠的变化 */
.active .line-box {
  transform: rotate(-45deg);
}
.active .line-box .line:first-child {
  transform: rotate(-90deg) translateX(1px);
}
.active .line-box .line:last-child {
  transform: rotate(-90deg) translateX(-1px);
}
/* 菜单列表的变化 */
.active .menu-list {
  opacity: 1;
  transform: scale(1);
}
.active .menu-list li {
  /* 执行动画：动画名 时长 线性 停留在最后一帧 */
  animation: fade-in-item 0.4s linear forwards;
}
/* 接下来为每一项设置动画延迟时间 */
.active .menu-list li:nth-child(1) {
  animation-delay: 0.1s;
}
.active .menu-list li:nth-child(2) {
  animation-delay: 0.2s;
}
.active .menu-list li:nth-child(3) {
  animation-delay: 0.3s;
}
.active .menu-list li:nth-child(4) {
  animation-delay: 0.4s;
}

/* 定义动画 */
@keyframes fade-in-item {
  100% {
    transform: translateX(0);
    opacity: 1;
  }
}
